Systems are commercially available that permit an operator to edit or modify the color and composition of an original image to form a more aesthetically pleasing reproduction of the image in hard copy form. One example of such a system is the KODAK PREMIER Image Enhancement System manufactured by the Eastman Kodak Company of Rochester, N.Y. The KODAK PREMIER Image Enhancement System incorporates a film reader unit to digitally scan original images in the form of negatives, transparencies or lithographic film and display the scanned original images at an operator workstation which includes a monitor, keyboard, and digitizing tablet, with accompanying stylus, coupled to a processing unit. An operator can utilize the workstation to alter the original images by cropping, rotating, resizing, changing the color balance, or performing a multitude of other manipulation functions. The altered original images are then reproduced in hard copy form by a writing unit.
In such a system, it is particularly desirable to incorporate an interactive electronic "airbrush" manipulation function in the reproduction apparatus, i.e., a function that permits the operator to retouch the original image displayed in video form on the monitor of the workstation in a manner similar to conventional airbrushing of photographic negatives or prints. For example, the operator can use the airbrush function to lighten, darken, change the contrast, or add color to selected areas of the displayed image. The electronic airbrush function, however, must closely model the operation of a conventional airbrush in both function and result in order to gain the acceptance of operators accustomed to their use.
Attempts to create an electronic airbrush function within a color image reproduction apparatus have met with only limited success to date, as conventional methods of electronically modeling the functions of a conventional mechanical airbrush as described above have not produced an electronic airbrush function which, in the eyes of conventional airbrush operators, realistically duplicates the use of a conventional mechanical airbrush. Accordingly, it is an object of the present invention to provide an airbrush modeling function for an electronic image reproduction system that realistically models the operation of a conventional mechanical airbrush in both function and result.